The assignee of the present application has engaged in research and development of electrodeposition of polyvinyl fluoride for the production of seamless belts and dielectric receivers. This technology uses the electrodeposition of a high solids polymer dispersion to obtain thick polymer films using non-complex equipment with low overall cost. The polymer dispersions can include polyvinyl fluoride (PVF) such as is sold by E.I. du Pont De Nemours & Co. under the name Tedlar.RTM. (including 33% by weight solids) or polyvinylidene difluoride (PVDF) such as is sold by Pennwalt Corp. under the name Kynar.RTM. (including 45% by weight solids). The dispersions are diluted with an appropriate solvent, and a condition chemical agent or solvent is added to obtain a uniform electrodeposited film.
The equipment typically used for such electrodeposition includes a conventional low voltage power supply, a metal mandrel having the appropriate dimensions for the seamless belt to be prepared, a metal or other appropriate counterelectrode and a tank to contain the dispersion. The dispersion is placed into the tank and the mandrel is then set in place with the counterelectrode placed in the center of the mandrel from top to bottom. Voltage is applied to the mandrel and counterelectrode with such a polarity as to electrodeposit the dispersion on the inside of the mandrel. For PVF, the mandrel acts as the cathode and for PVDF, the mandrel acts as the anode. After electrodeposition, the mandrel is removed from the dispersion and placed in an oven at an appropriate temperature to coalesce the dispersion particles to form a film and evaporate the solvent to give a dry, uniform film. Then, the mandrel is removed from the oven and allowed to cool to room temperature, after which the seamless belt is removed from the mandrel.
These seamless belts are not conductive and if they are to be used as photoreceptor substrates or dielectric receiver belts, a conductive coating of some type must be applied by an additional process step. For example, the assignee of the present application has developed a procedure in which a metal such as nickel is electrodeposited as a thin layer on the inside of a mandrel to form a conductive layer. Next, a polymer layer, e.g., PVF or PVDF, is electrodeposited to give mechanical stability, to form a photoreceptor substrate which may then be removed from the mandrel. After heating in an oven and cooling, the seamless belt with a thin metal coating is removed from the mandrel to give a conductive seamless belt. This process has disadvantages, e.g., it is necessary to electrodeposit a thin removable metal film on the inside of the mandrel. In addition, the mandrel may have to be passivated in some way so that the thin metal film does not permanently adhere to the mandrel surface. These process steps add to the overall cost of the conductive seamless belt.
U.S. Pat. No. 4,686,016 discloses a method of electrodepositing a metal coating onto a surface of an endless belt. An annular bath is formed by a pair of concentrically arranged endless belts and an aqueous electrolytic solution is filled into the annular bath. An anode is supported in the bath and one of the endless belts forms a cathode. The anode and cathode are connected to a constant voltage source and a metal coating is deposited on the belt acting as a cathode.
U.S. Pat. No. 4,758,486 discloses an endless belt-shaped electrophotographic photoconductor comprising a support material and an electroconductive layer deposited thereon by vacuum evaporation. The electroconductive overcoating layer may comprise a polymeric material having a glass transition temperature of -10.degree. C. or lower.
U.S. Pat. No. 4,270,656 discloses a method of forming a rubber and fabric feed belt comprising the steps of mounting a sleeve on a mandrel, placing the mandrel in a mold, pouring rubber into the mold, removing the formed belt, subjecting the belt to a halogenation treatment, and grinding the outer surface of the belt.
U.S. Pat. Nos. 3,927,463, 3,950,839 and 4,067,782, disclose various methods of forming an electroforming mandrel used in the production of endless seamless nickel xerographic belts.